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Pressing in on discs

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  • #73943
    Mel Sandberg
    Participant

    When I was a student, I recall learning that the discs on a pedal harp must be able to be pressed in slightly.

    #73944
    carl-swanson
    Participant

    Mel- Each disc on the harp is screwed onto a spindle-a steel bar that runs between the two action plates. Each spindle has a brass action arm pressed onto knurling on its shaft and the linkage is riveted to the action arm.

    The chain of movement in a pedal harp when you move a pedal is this: When you press your foot on the brass pedal, that moves the steel pedal bar inside the pedestal, which moves the pedal rod that runs up the column, which moves the main action gears at the column end of the action. Those gears divide the pedal rod movement between the natural and sharp chains, i.e., the linkage. The linkage moves the brass action arm which moves the spindle which moves the disc.

    Each spindle has a disc screwed onto it on the string side of the neck, and has a hollow back plate screw with a little spring in it pressing on it from the back plate side of the instrument. The head of the spindle is cone shaped and so the back plate screw presses the cone shaped spindle head into a cone shaped hole in the front plate. If the back plate screw is not pressing the spindle hard enough against the front plate, the spindle will chatter back and forth between the front and back plates when the string is plucked(and the disc engaged). If it is pressing the spindle too hard against the front plate, it can bind up the chain so it moves hard or not at all. So the trick is to adjust the back plate screw so it pushes the spindle head against the front plate hard enough to not chatter, but not so hard that it binds up the movement.

    Back plate screws have to be tighter(meaning pressing harder against the back end of the spindle) at the bass end of the action then higher up because the string tension is higher and the swing of the vibrating string is greater than higher on the instrument.

    When you press your thumb against the prongs of a disc, you’re checking to see how hard the back plate screw is pressing on the spindle. If you can’t press the spindle back at all, then the back plate screw is too tight and should be backed off a little.

    I’m sure that’s far more than you ever wanted to know about your harp action!

    #73945
    Mel Sandberg
    Participant

    Hi Carl, no, on the contrary, it is only a drop in the ocean.

    #73946
    kathy-chanik
    Participant

    Carl, I seem to remember a technician telling me you can get more sound out of the instrument

    #73947
    carl-swanson
    Participant

    In the middle and upper register of the instrument, if the backplate screw is not tight enough, you may not get that chattering but it can make the pitch kind of fuzzy and unclear. Tightening the backplate screw a bit can usually clear that up. It won’t give you more sound, just clearer sound. But something like that is best left to a qualified technician.

    #73948
    unknown-user
    Participant

    ” Does this apply to all harps, or only Lyon and Healys?

    Dear Mel,

    I believe that this applies to some harps, but not all. All older L&H would have this system.

    Salvi harps

    #73949
    carl-swanson
    Participant

    Lyon & Healy, Wurlitzer, Venus, Swanson, Aoyama all have this type action. Salvi and Camac do not. Newer Lyon & Healy Semi-grands have Salvi actions on them

    #73950
    unknown-user
    Participant

    Dear Mr Swanson,

    Thank-you

    #73951
    Mel Sandberg
    Participant

    Many thanks to everybody.

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